Frequency-dependent enhancement of fluid intelligence induced by transcranial oscillatory potentials

Curr Biol. 2013 Aug 5;23(15):1449-53. doi: 10.1016/j.cub.2013.06.022. Epub 2013 Jul 25.


Everyday problem solving requires the ability to go beyond experience by efficiently encoding and manipulating new information, i.e., fluid intelligence (Gf) [1]. Performance in tasks involving Gf, such as logical and abstract reasoning, has been shown to rely on distributed neural networks, with a crucial role played by prefrontal regions [2]. Synchronization of neuronal activity in the gamma band is a ubiquitous phenomenon within the brain; however, no evidence of its causal involvement in cognition exists to date [3]. Here, we show an enhancement of Gf ability in a cognitive task induced by exogenous rhythmic stimulation within the gamma band. Imperceptible alternating current [4] delivered through the scalp over the left middle frontal gyrus resulted in a frequency-specific shortening of the time required to find the correct solution in a visuospatial abstract reasoning task classically employed to measure Gf abilities (i.e., Raven's matrices) [5]. Crucially, gamma-band stimulation (γ-tACS) selectively enhanced performance only on more complex trials involving conditional/logical reasoning. The present finding supports a direct involvement of gamma oscillatory activity in the mechanisms underlying higher-order human cognition.

MeSH terms

  • Adult
  • Attention / physiology
  • Cognition / physiology
  • Female
  • Humans
  • Intelligence / physiology*
  • Male
  • Neuropsychological Tests
  • Nontherapeutic Human Experimentation
  • Time Factors
  • Transcranial Magnetic Stimulation* / methods
  • Young Adult